The objective of this proposal is to study the factors affecting polyamine biosynthesis within the framework of the intact cell. Asynchronous and synchronous HeLa cells will be used. The relationship between ornithine decarboxylase and production of putrescine measured in the intact cell will be studied. These experiments will involve the use of labeled ornithine and arginine and determination of the production and conversion rates of each amine. The effect of alteration in substrate and cofactor requirements will be studied. This program will also investigate the hypothesis that the regulation and expression of ornithine and S-adenosylmethionine decarboxylases have several features in common with emphasis on a) the relative importance of synthesis and degradation in determining enzyme levels, b) the mechanisms operating during the refractory and recovery periods, c) the question of whether the same protease is involved in the degradation of both enzymes.